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42.05 APPLICATION FOR PERMIT FOR SURFACE OR IINDERGROUND MINING ACTIVITIES -- MINIMUM REQUIREMENTS FOR OPERATION AND RECLAMATION PLANS. 2.05.6 Mitigation of Surface Coal Mining Operation Impacts. (Cont'd,) (6) (e) (Cont'd.) upon current state-of-the-art subsidence prediction technology, is presented in the Subsidence Appendix, Volume 3. It contains all of the specific information required by 2.05.6(b)(e). (i) (A) The mining method currently employed and planned for [he Orchard Valley and Orchard Valley West Mines is room and pillar mining with eventual pillar re- covery for most of the Permit Area. Exceptions are beneath the East Roatcap Creek and Steven's Gulch drainages cohere overburden thickness is less than 800 ft. In these specific areas, pro- tective pillars will be utilized, Re- fer to Section 2.05.6 (6)(f). The "D" coal seam deposit will be de- veloped by a series of main and submai.n • entryways (refer to the Five-Year Mine _ Plan, Map 2-4). Room and pillar panels will continue to be driven off the pri- mary set of entryways with total pillar recovery employed to the extent that safe mining conditions dictate. Where unsafe or hazardous conditions preclude total extraction, the pillars will be partially removed, which greatens the distance from the production site to the caveline. Eventually, pillars .sup- porting the main and submain entryways will be extracted, along with barrier pillars. In areas of partial pillar recovery, the remaining "stump", or portion not mined, fails and the roof falls. The safety advantage of partial pillaring is the temporary delay in planned roof falls. (B) The overburden of the permit area ranges in thickness from several hun- dred to slightly greater than 2000 ft. Revised 12/26/84 Revised 10/12/86 Revised 10{O1J87 151